Four interview tracks, one judge that grades every answer.
Work through DSA, LLD, HLD, and Core CS in one place. Write real code, size real systems, and defend your designs to an AI interviewer that probes back. Every attempt comes back as a verdict, a score, or a rubric.
No card required. Free DSA is the full 350-problem track with the real judge.
- 350DSA problems
- 16LLD machine-coding builds
- 16AI mock interviews
- 1judge across all four tracks
Four tracks, one judge
Each track has its own format and its own free tier. The judge and your progress carry across all of them.
DSA
350 problems · 29 modules
Statement, editorial, and a real judge on one screen.
- 150 foundations + 200 interview problems
- 29 modules, from basics to DP
- Run and submit on a real judge
LLD
16 builds · hidden tests
Implement the class, then pass the hidden behavioral tests. LRU cache up to Splitwise.
- Class-skeleton starters
- Hidden design tests
- Same judge pipeline
HLD
16 lessons · 15 drills · 16 mocks
Learn the fundamentals, break real systems into diagrams, size them with estimation drills, then defend a design to an AI interviewer.
- 11 interactive system breakdowns
- 15 auto-graded estimation drills
- 16 AI-interviewer mock cases
Core CS
165 MCQs · 105 flashcards
OS, Networks, and DBMS: interview-focused articles, explained MCQs, and spaced-repetition flashcards for rapid-fire rounds.
- 18 interview-focused articles
- 165 explained MCQs
- 105 SM-2 flashcards
How a session actually goes
Three things happen on repeat: you attempt, you submit, and the judge tells you exactly where you stand.
Practice LLD by building it
Every machine-coding problem ships a class skeleton and hidden behavioral tests that hammer the edge cases, from LRU cache to Splitwise. An AC means the design actually holds up.
Rehearse with an AI interviewer
Answer HLD case studies in free text, field one probing follow-up per stage, and get a rubric-graded scorecard at the end. Run as many mocks as you want.
Get a real verdict, fast
Run the samples, submit against the hidden tests, and see AC, WA, or TLE in seconds. Your progress syncs across DSA, LLD, HLD, and Core CS.